The need to dispose of plutonium derived from the dismantlement of nuclear weapons is a serious problem. One step which can be taken to alleviate this problem is to recycle weapons-grade plutonium as fuel for a nuclear reactor power plant. This solution requires that the plutonium be transported from the weapons site to the fuel fabrication facility. However, this prospect raises the concern about the best method for plutonium shipment and storage from both the safety and diversion standpoints.
Historically, plutonium has been shipped as the metal, nitrate or oxide. The metal form must be shipped within an inert atmosphere to prevent oxidation. In a postulated accident, the plutonium metal would be difficult to disperse into the environment because of its dense form. However, if the plutonium metal comes into contact with air, it can oxidize or burn and thus form the oxide. The oxide is a fine powder which could be readily dispersed into the environment. Furthermore, plutonium metal is ideal for fabrication of nuclear weapons and is thus highly susceptible as a target for diversion. The nitrate is a liquid which is slightly more resistant to diversion but can be easily dispersed into the environment in the event that the storage container is breached during an accident or act of sabotage. The oxide is generally shipped as a fine powder which is more resistant to diversion than is the liquid nitrate. However, the oxide can also be easily dispersed into the environment if the storage container breaks open during an accident or act of sabotage. Thus, there is a need for a safe and secure method for transporting weapons-grade plutonium to the fuel fabrication facility.
Previous mixed-oxide fuel fabrication has relied on fine plutonia feed powders usually converted from plutonium nitrate solutions to the oxide by direct precipitation processes or as a co-precipitated compound with uranium. These conversion processes result in a very fine powder that is blended with urania to produce mixed-oxide feed material. In some cases, this blended material has been milled by a high-energy process to improve the plutonium dispersion. Statistical sampling and metallographic examination techniques are utilized to qualify each powder blend. One hundred percent inspection techniques are utilized to verify that gross plutonium dispersion did not occur in any portion of a completed fuel rod.